问为什么Datepicker不起作用？

EN

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="priceLists.aspx.cs" Inherits="PriceWorx.priceLists" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1/themes/base/jquery-ui.css"
        rel="stylesheet" type="text/css" />
    <link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.6/themes/blitzer/jquery-ui.css"
        rel="Stylesheet" type="text/css" />
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js" type="text/javascript"></script>
    <script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.0/jquery-ui.js" type="text/javascript"></script>
    <script type="text/javascript">


        $(function () {
            $("#tabs").tabs({ collapsible: true });

            $("#tabs").tabs({ event: "mouseover" });     
            $('#datepicker').datepicker({
                minDate: "0",
                changeMonth: true,
                changeYear: true

            });

        });

    </script>
</head>
<body>
    <form id="form1" runat="server">
    <!-- all tabs -->
    <div id="tabs" class="ui-tabs ui-widget ui-widget-content ui-corner-all">
        <!-- tab definitions -->
        <ul>
            <li><a href="#tabs-1" class="dynamic">foo</a></li>
            <li><a href="#tabs-2">bar</a></li>
        </ul>
        <div id="tabs-1" style="width: 100%;">
            <div>
                <p>
                    Date:
                    <input type="text" id="datepicker" /></p>
            </div>
        </div>
        <div id="tabs-2">
            <table style="width: 100%;">
                <tr valign="top" align="center">
                    <td style="width: 100%;" colspan="4">
                        bar
                    </td>
                </tr>
            </table>
        </div>
    </div> 
    </form>
</body>
</html>